Inhibitory Effects of Thyme and Ajowan Oils on Growth of Aspergilus parasiticus on Pear During Cold Storage

The inhibitory effects of thyme and ajowan oils on growth of A. parasiticus on pear during cold storage were studied. The main components of the two essential oils are phenolic compounds such as thymol and carvacrol with antimicrobial properties. Pear samples were inoculated by suspension ( 106 spor/ml) of A. parasitcus spores and sprayed by thyme (200 p.p.m) and ajowan (300p.p.m) separately and kept in cold storage (0 ±10C and relative humidity of 85%). Organoleptic test for evaluating oil odor residue was studied after 3 months. The amount of spoilage and contamination of pear fruit in 1st, 2nd, and 3nd month after cold storage was determined and were data the statistically analyzed. The results showed that in spite of the higher thymol content in ajowan oil constituent, which is well known as an antimicrobial agent Stronger than thyme oil, thyme oil at 200 p.p.m was more effective than ajowan oil in controlling and preventing, A.parasiticus growth in pear. It seems this is due to synergistic effects of other phenolic compounds such as carvacrol which does not exist in ajowan oil. The results of organoleptic test showed that the samples treated with ajowan oil have more acceptance than those treated with thyme oil thie applied even to the control sample. According to the results, thyme and ajowan oils are good promising natural antifungal agents without any hazardous effects on human health and can be successfully use as chemical fungicides.